The benefits of regular aerobic exercise are well established. However, due to time constraints, inclement weather, and other reasons, many people are prevented from aerobic activities such as walking, jogging, running, and swimming. In response, a variety of exercise equipment has been developed for aerobic activity. It is generally desirable to exercise a large number of different muscles over a significantly large range of motion so as to provide for balanced physical development, to maximize muscle length and flexibility, and to achieve optimum levels of aerobic exercise. It is further advantageous for exercise equipment to provide smooth and natural motion, thus avoiding significant jarring and straining that can damage both muscles and joints.
While various exercise systems are known in the prior art, these systems suffer from a variety of shortcomings that limit their benefits and/or include unnecessary risks and undesirable features. For example, stationary bicycles are a popular exercise system in the prior art; however, these machines employ a sitting position that utilizes only a relatively small number of muscles, through a fairly limited range of motion. Cross-country skiing devices are also utilized to simulate the gliding motion of cross-country skiing. While cross-country skiing devices exercise more muscles than stationary bicycles, the substantially flat shuffling foot motion provided by the ski devices limits the range of motion of some of the muscles being exercised. Another type of exercise device simulates stair climbing. These devices exercise more muscles than stationary bicycles; however, the rather limited range of up-and-down motion utilized does not exercise the user's leg muscles through a large range of motion. Treadmills are still a further type of exercise device in the prior art. Treadmills allow natural walking or jogging motions in a relatively limited area. A drawback of the treadmill, however, is that significant jarring of the hip, knee, ankle and other joints of the body may occur through use of this device.
A further limitation of a majority of exercise systems in the prior art lies in the limits in the types of motions that they can produce. A relatively new class of exercise devices is capable of producing elliptical motion. Exercise systems create elliptical motion, as referred to herein, when the path traveled by a user's feet while using the exercise system follows an ellipse-shaped path of travel. Elliptical motion is much more natural and analogous to running, jogging, walking, etc., than the linear-type, back and forth motions produced by some prior art exercise equipment.
One drawback of exercise systems that create elliptical motion is that a user's feet are constrained to travel through a path that is substantially limited in terms of size and configuration from one user to the next. While some exercise devices of the prior art attempt to provide adjustable features, these attempts are crude and inconvenient to use.
What would thus be desirable is an exercise device that provides for smooth natural action, exercises a relatively large number of muscles through a large range of elliptical motion, and provides for safety and stability. Such an exercise device would further provide adjustable features that are convenient to use.